Earlier this month, AstraZeneca announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug designation for the investigational MEK1/2 inhibitor selumetinib for adjuvant treatment of patients with stage III or IV differentiated thyroid cancer.

Selumetinib inhibits the MEK pathway in cancer cells to prevent tumor growth. It is being tested in the phase III ASTRA trial in patients with differentiated thyroid cancer who are at high risk of recurrence. In a phase II investigation of selumetinib in patients with advanced thyroid cancer, clinically meaningful increases in iodine uptake and retention were seen in patients with thyroid cancer that was refractory to radioactive iodine.

Underlying Mechanism

Selumetinib is being tested for its ability to increase expression of sodium/iodine symporter, which is important for radioactive iodine uptake into thyroid cells, with the potential to add a treatment option for patients who do not respond well to radioactive iodine.

Sean Bohen, Executive Vice President of Global Medicines Development and Chief Medical Officer at AstraZeneca, said: “Uptake of radioactive iodine is crucial for patients with thyroid cancer where no other therapies have proven beneficial. Selumetinib could significantly enhance currently available treatment options for these patients. The Orphan Drug designation is an important achievement as we advance our development plans for this potential treatment in differentiated thyroid cancer.”

Orphan Drug Designation Program

The Orphan Drug designation program provides orphan status to drugs and biologics, which are defined as those intended for the safe and effective treatment, diagnosis, or prevention of rare diseases or disorders that affect fewer than 200,000 people in the United States.

Differentiated thyroid cancer is diagnosed in approximately 60,000 people in the United States each year, and radioactive iodine therapy is recommended for those with known or suspected metastases at diagnosis as well as for those at high risk of ­recurrence. ■